{"id":"CVE-2026-64214","summary":"powerpc/time: Remove redundant preempt_disable|enable() calls from arch_irq_work_raise()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\npowerpc/time: Remove redundant preempt_disable|enable() calls from arch_irq_work_raise()\n\nA kernel panic is observed when handling machine check exceptions from\nreal mode.\n\n  BUG: Unable to handle kernel data access on read at 0xc00000006be21300\n  Oops: Kernel access of bad area, sig: 11 [#1]\n  MSR:  8000000000001003 \u003cSF,ME,RI,LE\u003e  CR: 88222248  XER: 00000005\n  CFAR: c00000000003ffc4 DAR: c00000006be21300 DSISR: 40000000 IRQMASK: 0\n  NIP [c000000000029e40] arch_irq_work_raise+0x10/0x70\n  LR [c00000000003ffc8] machine_check_queue_event+0xa8/0x150\n  Call Trace:\n  [c0000000179d3c70] [c00000000003ff64] machine_check_queue_event+0x44/0x150\n  [c0000000179d3d30] [c0000000000084e0] machine_check_early_common+0x1f0/0x2c0\n\nThe crash occurs because arch_irq_work_raise() calls preempt_disable()\nfrom machine check exception (MCE) handlers running in real mode. In\nthis context, accessing the preempt_count can fault, leading to the panic.\n\nThe preempt_disable()/preempt_enable() pair in arch_irq_work_raise()\nwas originally added by commit 0fe1ac48bef0 (\"powerpc/perf_event: Fix\noops due to perf_event_do_pending call\") to avoid races while raising\nirq work from exception context.\n\nLater, commit 471ba0e686cb (\"irq_work: Do not raise an IPI when\nqueueing work on the local CPU\") added preemption protection in\nirq_work_queue() path, while commit 20b876918c06 (\"irq_work: Use per\ncpu atomics instead of regular atomics\") added equivalent\nprotection in irq_work_queue_on() before reaching arch_irq_work_raise():\n\n  irq_work_queue() / irq_work_queue_on()\n    -\u003e preempt_disable()\n      -\u003e __irq_work_queue_local()\n        -\u003e irq_work_raise()\n          -\u003e arch_irq_work_raise()\n\nAs a result, callers other than mce_irq_work_raise() already execute\nwith preemption disabled, making the additional\npreempt_disable()/preempt_enable() pair in arch_irq_work_raise()\nredundant.\n\nThe arch_irq_work_raise() function executes in NMI context when called\nfrom MCE handler. Hence we will not be preempted or scheduled out since\nwe are in NMI context with MSR[EE]=0. Therefore, it is safe to remove\nthe preempt_disable()/preempt_enable() calls from here.\n\nRemove it to avoid accessing preempt_count from real mode context.\n\n[Maddy: Fixed the commit title]","modified":"2026-07-27T04:03:20.548157048Z","published":"2026-07-24T15:23:03.529Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64214.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/31467b23823ffec1f6fff407f8e3ca9af8b7491a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/51860e423592893cd7bfa7287d99a3aff4dc3a9d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6dcd072a5ae3aed336e4a67a7d4cc5205b240065"},{"type":"WEB","url":"https://git.kernel.org/stable/c/72d8d1c36452a4d3ee134b1da48de7518c1329f9"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8079acc5ee5235a627e4586d4f42082a9000ea64"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a09d07ac45e283c9861a9ceea06f56d0ba851d22"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64214.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64214"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"cc15ff3275694fedc33cd3d53212a43eec7aa0bc"},{"fixed":"51860e423592893cd7bfa7287d99a3aff4dc3a9d"},{"fixed":"a09d07ac45e283c9861a9ceea06f56d0ba851d22"},{"fixed":"72d8d1c36452a4d3ee134b1da48de7518c1329f9"},{"fixed":"6dcd072a5ae3aed336e4a67a7d4cc5205b240065"},{"fixed":"8079acc5ee5235a627e4586d4f42082a9000ea64"},{"fixed":"31467b23823ffec1f6fff407f8e3ca9af8b7491a"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64214.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.18.0"},{"fixed":"6.1.175"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.142"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.92"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.34"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.0.11"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64214.json"}}],"schema_version":"1.7.5"}